In general, used in an image forming apparatus such as a printer, a facsimile machine, and a multifunction peripheral (MFP) is a developer amount detection device that detects the amount of a toner as a developer contained in a development device. For example, proposed is a developer amount detection device that detects the amount of a toner inside a development device by using the rotation time (cycle) of a rotating part (stirring bar) of the developer amount detection device that changes according to the amount of the toner inside the development device (for example, see Patent Document 1).